City, owned by the Abu Dhabi United Group since 2008, spent £215 million, the biggest sum by any club in any window. They are not, however, to face any action.
Qatari-owned PSG followed their world record £200 million purchase of Neymar with a loan deal for Kylian Mbappé which will be translated into a £165.7m deal next summer.
PSG are being looked at and face potentially stiff penalties.
But as Arsenal manager Arsene Wenger warned: “Once a country owns a club, everything is possible.”
Wenger was a huge fan of FFP now says it should be scrapped as he argued: “You should not have a rule that cannot be imposed.”
But why is Wenger getting so upset when UEFA have already announced they are investigating PSG?
It is because he does not believe the Ligue 1 club will serve the time to fit the crime. They seem to have no fear of spending money.
The complexities of FFP are varied and vast, but what is it? Why do we have it? And how do clubs get round it? And what happens to them when they are found out?
Financial Fair Play was the brainchild of the now widely disgraced former UEFA chief Michel Platini.
Worried by the growing collective debt in European football seven years ago the former French midfield legend believed he had to help clubs live within their means.
Failure to comply would exclude clubs from competing in the Champions League and Europa League.
And, in broad terms, the 2011 agreement seems to have worked.
While barely a handful of top flight clubs were in profit five years ago, the majority of them make money now and is why this summer's transfer spending was able to exceed £1 billion.
The story is similar when taking European football as a whole.
The most recent figures available displayed a collective profit of €1.5 billion – up from losses of €700 million just after FFP was imposed.
In short, since 2011, clubs have had to ‘break even' over a three-year period to avoid being penalised.
This ‘break even' figure only applies to football-related expenditure – what goes out in terms of wages and transfers needs to be covered by television revenue, ticket sales and endorsements.
Benefactors can also still spend at will on facilities and youth development.
The sponsorship factor is a bone of contention for many critics.
The recent protest by La Liga to UEFA about the financial dealings of City and PSG specified that both clubs benefited from unrealistic sponsorship deals that “make no economic sense and lack any fair value”
A statement added: “PSG and Man City’s funding by state-aid distorts European competitions and creates an inflationary spiral that is irreparably harming the football industry. UEFA must enforce FFP regulations to avoid discrimination among clubs.”
Benefactors can also still spend at will on facilities and youth development within FFP rules.
To further muddy the water, the ‘break-even' element states clubs can spend €30m more than they earn over a three-year period.
To quote the UEFA guidelines: ‘Clubs can spend up to €5million more than they earn per assessment period (three years). However, it can exceed this level to a certain limit, if it is entirely covered by a direct contribution/payment from the club owner(s) or a related party. This prevents the build-up of unsustainable debt.
The limits are €30 million for assessment periods 2015/16, 2016/17 and 2017/18.
This three-year period of assessment means we have to look at transfer deals very closely to assess the financial implications of a transfer.
Manchester City Fees Breakdown
In the case of City's €45 million purchase of Bernardo Silva on a five-year deal, it will be calculated at €9 million per season and not the full sum for this summer.
It should also be noted City also sold players from Kelechi Iheanacho to Wilfried Bony and their net spend was nearer £130million.
And so long as the bank balance is in the black all is well for far as FFP is concerned.
Another factor, however, is the new ‘soft' salary caps kicking in which effectively made Arsenal's window so difficult this summer as they bid to play by the rules.
To prevent increased television money going straight out of the clubs and into the pockets of players and agents short-term cost control regulations have been implemented.
They boil down to clubs being restricted from raising their wage bill by more than £7 million from one season to the next.
PSG claim their books balance and they can prove it.
And should they be worried if they can't?
In 2014 PSG and City were docked €20 million of their Champions League prize money and allowed to select only 21 players in their squads for the competition for one season.
That hardly made them suffer, so what will change now? Will UEFA back calls from La Liga and co. and hit them with bigger penalties such as Champions League expulsion if found guilty this time?
Only time will tell, but it would seem unlikely.
And it is not just in England and France that clubs have had more than the support of wealthy individuals.
Last year, Real Madrid and Barcelona topped a list of seven Spanish sides which had to repay millions of Euros in of state aid.